The neutering of certain animals is desirable for a great variety of reasons. Certain animals are used primarily as pets and the indiscriminant reproduction by such animals has created problems for animal control agencies and grave concerns by others.
Other animals are used primarily as a source of meat and neutering of such animals is desirable since reproductive functions by such animals are unnecessary and in many instances undesirable. For example, the meat of certain reproductively active male animals (such as male pigs or boars) has an objectionable odor and unpleasant taste which makes the meat unacceptable to consumers. The source of this odor and taste is a compound produced from testosterone (the major sex steroid in males) which saturates such meat. The only known procedure for providing consumer acceptable meat from such male animals is castration at a time sufficiently prior to slaughter such that testosterone production is halted and the compound producing the objectionable odor and unpleasant taste has been removed from the meat of the neutered animal by natural body functions.
It is conventional practice in the swine industry, and certain other meat production industries, to castrate all males intended for meat production and this procedure is usually performed when the males are from 7 to 14 days old. Such castration is currently accomplished in the swine industry by a surgical procedure to which there are several objections. Firstly, such surgical procedures greatly increase the likelihood of infection and may cause other health problems. Secondly, some have raised objections to such surgical procedures contending that they are inhumane.
For the foregoing reasons, it is an object of the present invention to provide for the neutering of animals without the necessity of a surgical procedure and in a manner to which objections for humane reasons would not be raised.
A more specific object of the present invention is to provide a process for the immunological neutering of animals which is simple, safe and effective.
Gonadotropin releasing hormone, a peptide hormone produced in the brain of animals, controls reproductive functions by influencing the synthesis and release of hormones from the pituitary gland necessary for sexual development, maintenance and reproduction. It has been previously proposed that an immunological response could be obtained by combining gonadotropin releasing hormone with a foreign protein and injecting certain animals with this combination. In this regard, experiments involving the injection of adult male rabbits, adult male rats, adult male and female monkeys and adult ewes with gonadotropin releasing hormone combined with a foreign protein have been reported. According to such reports, repeated injections of this combination have caused a noticeable decline in luteinizing hormone and follicle-stimulating hormone as well as testicular regression due to atrophy of the testes and secondary sex organs and an end to ovarian cycles.
While recognizing the immunological reaction, these previous experiments have not resulted in any acceptable techniques or procedures that could be utilized as a solution to the aforementioned problem. These reported experiments require repeated injections over a considerable time period (up to 12 months in some cases) and the results achieved were mixed.